1. Field of the Invention
This invention relates to a process for treating a substance containing microorganisms to render the microorganisms inactive. More particularly, this invention relates to process and apparatus for treating liquid-like substances such as sewage, chemical waste, liquid mining material, etc., to kill the microorganisms therein.
2. Description of the Prior Art
Numerous methods and apparatus are known in the prior art for treating materials to render inactive the microorganisms therein. In addition to the well known, but time-consuming processes such as pasteurization, bacterial action, and the like, it is known in the prior art to employ high frequency electromagnetic wave energy to irradiate a liquid for rendering inactive the microorganisms therein. It is also known to employ pulsed electrical discharge between electrodes to effect neutralization of the microorganisms in the liquid in which the electrodes are disposed. Such electrical discharge between electrodes is commonly referred to as electrohydraulic discharge. One of the difficulties of the electrohydraulic discharge has been the containment of the relatively tremendous localized pressures developed by the electrohydraulic discharge. That is, either the electrohydraulic discharge must be on a very small scale such as between closely adjacent electrodes for purifying lines and the like, or if vessels of appreciable size were employed to enclose the liquid to be treated, the vessels had to be structurally strong, and hence expensive, to contain the force generated by the electrohydraulic discharge of an intensity lethal to the microorganisms. The prior art electrohydraulic methods required that the strong vessel be closed and hence required a batch process and was not susceptible to a wide variety of processes such as the continuous or modified batch-continuous operation.
One of the particular problems that has bothered the prior art apparatus employing electrohydraulic discharges has been the problems with the electrohydraulic electrodes. Since the electrodes were rapidly eroded, they were deformed by the shock wave produced by the electrohydraulic discharge, or were blown from the region where the electrohydraulic discharge was effected. Thus, it can be seen that the prior art methods and apparatus have not been completely satisfactory in effecting treatment of large volumes of material such as the effluent to or from a sewage plant.
It is a primary object of this invention to provide method and apparatus for treating a substance to kill the microorganisms therein that obviate the disadvantages of the prior art methods and apparatus.
It is a particular object of this invention to provide apparatus for treating a liquid-like substance to kill microorganisms therein that is operable in either continuous, batch, or batch-continuous processes and that avoids the necessity for closed, thick-walled vessels with high structural strength to contain the electrohydraulic discharge employed in the treatment.
In this regard, it is also a particular object of the invention to provide a preferred form of electrohydraulic electrodes that minimizes deletrious erosion of the electrodes and alleviates the problem with deforming or blowing the electrodes from the region wherein the electrohydraulic discharge is effected, and to provide preferred magnetic field generating structure for effecting the desired shape of the magnetic field for containing and directing the electrohydraulic discharge.
This invention employs both the electrohydraulic discharge and the magnetic field and, hence, may be employed to treat a wide variety of substances, particularly where the magnetic field is itself lethal to the microorganisms contained therein. Ordinarily, however, best results are obtained from the electrohydraulic discharge if the substance is in the form of a liquid-like substance which can be flowed through the volumetric region with which the electrohydraulic discharge is associated and within the magnetic field generating structure. The term "liquid-like" is used herein to mean any substance that behaves like a liquid, including but not limited to liquids, liquids having solids or semisolids therein, slurries, and suspensions. The invention may be employed in a wide variety of fields of technology, including the treatment of juices and food slurries, the sterilization of waste, and extraction of minerals from brines, biological or chemical slurries and the like. It will be discussed herein, however, in a specific aspect of treating sewage for purposes of simplicity.
Liquid-like substances are preferable since they are readily flowed through a volumetric region in association with the electrohydraulic discharge electrodes and within the magnetic field. Also, the shock wave of the electrohydraulic discharge becomes steeper and more nearly approaches infinity in slope in a liquid, particularly where the liquid has some electrical conductivity. The invention can improve the extraction of elements from solution as originally mentioned in U.S. Pat. No. 3,220,873, issued Nov. 30, 1965. This technique will begin to cause a separation of material due to specific gravity and magnetic susceptibility. Also the "in line" electrodes are used to establish a continuous closed system flow. Firing of the ignitrons will be in a sequence based upon flow velocity and so that each volume of fluid will be treated more than once at a predetermined energy level.